The Experts below are selected from a list of 132 Experts worldwide ranked by ideXlab platform

Franck Chollet - One of the best experts on this subject based on the ideXlab platform.

  • optical detection for Droplet Size control in microfluidic Droplet based analysis systems
    Sensors and Actuators B-chemical, 2006
    Co-Authors: Namtrung Nguyen, Sumantri Lassemono, Franck Chollet
    Abstract:

    Abstract This paper reports on a hybrid polymeric microfluidic device with optical detection for Droplet-based systems. The optical part of the device is integrated by a hybrid concept. The microfluidic structures were fabricated using CO 2 laser on poly methylmethacrylate (PMMA) substrate. The microfluidic network consists of two microchannels for forming Droplets of an aqueous liquid in an immiscible carrier liquid. The optical component consists of two optical fibers for guiding laser light from the source, through the detection point, to a photo diode. The formed Droplets pass the detection point and diffract the incoming laser light. The detected signal at the photo diode can be used for evaluating Droplet Size, Droplet shape, and Droplet formation frequency. The device can detect very high formation frequencies, which are not detectable using a conventional CCD camera/microscope setup.

  • optical detection for Droplet Size control in microfluidic Droplet based analysis systems
    International Conference on Solid-State Sensors Actuators and Microsystems, 2005
    Co-Authors: Namtrung Nguyen, Sumantri Lassemono, Franck Chollet
    Abstract:

    We report for the first time a hybrid polymeric microfluidic device with optical detection for microfluidic Droplet-based systems. The device consists of a fluidic part and an optical part. Microchannels were fabricated using CO/sub 2/ laser. The microfluidic part consists of two microchannels for forming Droplets of an aqueous liquid in an immiscible carrier liquid. The optical part consists of two optical fiber for light emission and light detection. MicroDroplets are formed, when the aqueous liquid is injected into the carrier flow. The formed bubbles pass the optical detection and diffract some of the incoming light. The detected signal from the other optical fiber can be evaluated for Droplet Size, Droplet shape, and Droplet formation frequency.

Namtrung Nguyen - One of the best experts on this subject based on the ideXlab platform.

  • optical detection for Droplet Size control in microfluidic Droplet based analysis systems
    Sensors and Actuators B-chemical, 2006
    Co-Authors: Namtrung Nguyen, Sumantri Lassemono, Franck Chollet
    Abstract:

    Abstract This paper reports on a hybrid polymeric microfluidic device with optical detection for Droplet-based systems. The optical part of the device is integrated by a hybrid concept. The microfluidic structures were fabricated using CO 2 laser on poly methylmethacrylate (PMMA) substrate. The microfluidic network consists of two microchannels for forming Droplets of an aqueous liquid in an immiscible carrier liquid. The optical component consists of two optical fibers for guiding laser light from the source, through the detection point, to a photo diode. The formed Droplets pass the detection point and diffract the incoming laser light. The detected signal at the photo diode can be used for evaluating Droplet Size, Droplet shape, and Droplet formation frequency. The device can detect very high formation frequencies, which are not detectable using a conventional CCD camera/microscope setup.

  • optical detection for Droplet Size control in microfluidic Droplet based analysis systems
    International Conference on Solid-State Sensors Actuators and Microsystems, 2005
    Co-Authors: Namtrung Nguyen, Sumantri Lassemono, Franck Chollet
    Abstract:

    We report for the first time a hybrid polymeric microfluidic device with optical detection for microfluidic Droplet-based systems. The device consists of a fluidic part and an optical part. Microchannels were fabricated using CO/sub 2/ laser. The microfluidic part consists of two microchannels for forming Droplets of an aqueous liquid in an immiscible carrier liquid. The optical part consists of two optical fiber for light emission and light detection. MicroDroplets are formed, when the aqueous liquid is injected into the carrier flow. The formed bubbles pass the optical detection and diffract some of the incoming light. The detected signal from the other optical fiber can be evaluated for Droplet Size, Droplet shape, and Droplet formation frequency.

Bui T.h. - One of the best experts on this subject based on the ideXlab platform.

  • Surface Acoustic Mode Aluminum Nitride Transducer for micro-Size liquid sensing applications
    2018
    Co-Authors: Bui T.h.
    Abstract:

    The thesis focuses on the investigation of thin-film surface acoustic wave (SAW) devices for liquid sensing applications. The piezoelectric material is a thin film of Aluminum Nitride (AlN), a CMOS compatible material, deposited by pulse DC reactive sputtering technique. A CMOS compatible process is developed and employed to fabricate the AlN/Si surface acoustic wave (SAW) devices which operate in a liquid medium. The applicability of the SAW device in sensing liquid is proved by numerical analysis, simulations and experimental results.In the first chapter, the development of liquid sensors based on MEMS fabrication is introduced together with the wide range of applications for these devices. Also, the motivation to investigate the SAW device based on thin film AlN for liquid sensing is presented. In chapter 2, sensing mechanisms in general and applicable mechanisms of SAW sensors for liquid are presented. To determine the most suitable design of the SAW devices, three-dimension (3D) modeling based on the finite element method (FEM) is performed and analyzed.Chapter 3 reports on the effect of a micro-Size Droplet shape, specifically the liquid contact angle, radius (area) and wettability of the contact surface on the SAW response. The numerical analysis and experimental results explain the interaction mechanism between the attenuated SAW beam and micro-Droplets. The beam, which is emitted into the Droplet, is expressed by the fraction coefficient. The change in contact radius influences the fraction coefficient more than the change in contact angle, especially on hydrophilic and super-hydrophilic surfaces. In chapter 4, the first applicability of the SAW sensor is demonstrated by identifying the kind of liquid present on the propagation path. The sensing mechanism is based on physical properties (liquid density, sound speed in liquid and evaporation rate) and mass loading (concentration of stagnant liquid molecules). This also suggests a potential method to identify liquid samples of microliter volumes in microfluidic biosensors based on this SAW device.In chapter 5, a SAW device equipped with an embedded microhole is proposed for the control and monitoring of the contact area between the piezoelectric material and the liquid medium. The device is miniaturized to be integrated on a printed circuit board (PCB). The device response to changes in density and pressure as well as to the evaporation of the liquid inside the microhole is studied. These initial indirect experimental results show the applicability of the SAW device for the state of liquid flow inside the microhole. In chapter 6, some optimized structures of the SAW device are proposed. The simulation and experimental results showed that SAW devices with circular shape FIDTs have better performance, and provide a good method to detect micro-Size Droplets due to the better concentration of the energy traveling through the propagation path. Also in this chapter, a mixing IDT structure for SAW devices, which includes two layers of input IDTs, is proposed to reduce the longitudinal component in SAWs and generate novel mixing acoustic waves by mixing surface waves and plate waves on the piezoelectric material. Finally, in chapter 7 concluding remarks and recommendations for future work are given.

  • Surface Acoustic Mode Aluminum Nitride Transducer for micro-Size liquid sensing applications
    2018
    Co-Authors: Bui T.h.
    Abstract:

    The thesis focuses on the investigation of thin-film surface acoustic wave (SAW) devices for liquid sensing applications. The piezoelectric material is a thin film of Aluminum Nitride (AlN), a CMOS compatible material, deposited by pulse DC reactive sputtering technique. A CMOS compatible process is developed and employed to fabricate the AlN/Si surface acoustic wave (SAW) devices which operate in a liquid medium. The applicability of the SAW device in sensing liquid is proved by numerical analysis, simulations and experimental results.In the first chapter, the development of liquid sensors based on MEMS fabrication is introduced together with the wide range of applications for these devices. Also, the motivation to investigate the SAW device based on thin film AlN for liquid sensing is presented. In chapter 2, sensing mechanisms in general and applicable mechanisms of SAW sensors for liquid are presented. To determine the most suitable design of the SAW devices, three-dimension (3D) modeling based on the finite element method (FEM) is performed and analyzed.Chapter 3 reports on the effect of a micro-Size Droplet shape, specifically the liquid contact angle, radius (area) and wettability of the contact surface on the SAW response. The numerical analysis and experimental results explain the interaction mechanism between the attenuated SAW beam and micro-Droplets. The beam, which is emitted into the Droplet, is expressed by the fraction coefficient. The change in contact radius influences the fraction coefficient more than the change in contact angle, especially on hydrophilic and super-hydrophilic surfaces. In chapter 4, the first applicability of the SAW sensor is demonstrated by identifying the kind of liquid present on the propagation path. The sensing mechanism is based on physical properties (liquid density, sound speed in liquid and evaporation rate) and mass loading (concentration of stagnant liquid molecules). This also suggests a potential method to identify liquid samples of microliter volumes in microfluidic biosensors based on this SAW device.In chapter 5, a SAW device equipped with an embedded microhole is proposed for the control and monitoring of the contact area between the piezoelectric material and the liquid medium. The device is miniaturized to be integrated on a printed circuit board (PCB). The device response to changes in density and pressure as well as to the evaporation of the liquid inside the microhole is studied. These initial indirect experimental results show the applicability of the SAW device for the state of liquid flow inside the microhole. In chapter 6, some optimized structures of the SAW device are proposed. The simulation and experimental results showed that SAW devices with circular shape FIDTs have better performance, and provide a good method to detect micro-Size Droplets due to the better concentration of the energy traveling through the propagation path. Also in this chapter, a mixing IDT structure for SAW devices, which includes two layers of input IDTs, is proposed to reduce the longitudinal component in SAWs and generate novel mixing acoustic waves by mixing surface waves and plate waves on the piezoelectric material. Finally, in chapter 7 concluding remarks and recommendations for future work are given.Electronic Components, Technology and Material

  • Effect of Droplet shrinking on surface acoustic wave response in microfluidic applications
    'Elsevier BV', 2017
    Co-Authors: Bui T.h., Nguyen V.c., Vollebregt S., Morana B., Van Zeijl H.w., Chu Duc Trinh, Sarro P.m.
    Abstract:

    The effect of the contact angle and radius of a microSize Droplet on the surface acoustic wave (SAW) response for microfluidic applications is reported. It is studied through the dynamic change of the Droplet shape during the evaporation process. An aluminium nitride SAW device, operating at 125.7 MHz, is utilized to investigate the deformation of the Droplet shape (contact angle and contact radius) caused by shrinking. The large cavity placed on the propagation path distorts the in-band SAW response one time at the centre frequency. The fractional coefficient of the SAW insertion loss, before and after dropping the liquid on the propagation path, is continuously recorded. The change in the fractional coefficient shows that the radiated acoustic kinetic energy depends on the contact area between the sessile micro-Size Droplet and the SAW device more than the contact angle of the Droplet. Three Droplet volumes have been considered, namely 0.05, 0.1 and 0.13 μl, and the electrical results show a better agreement with the theoretical data than the optical image data. The average duration of the fractional coefficient change for these cases is 420, 573 and 760 s, respectively. The effect of the hydrophobicity versus hydrophilicity of the contact surface on the duration of the fractional coefficient change is studied by coating the SAW with a silicon oxide or hexamethyldisilazane (HMDS) thin layer. For the same 0.05 μl sessile Droplet on the hydrophobic surface, this duration is on average 110 s longer than that on the hydrophilic surface.Accepted author manuscriptElectronic Components, Technology and MaterialsEKL-User

Sumantri Lassemono - One of the best experts on this subject based on the ideXlab platform.

  • optical detection for Droplet Size control in microfluidic Droplet based analysis systems
    Sensors and Actuators B-chemical, 2006
    Co-Authors: Namtrung Nguyen, Sumantri Lassemono, Franck Chollet
    Abstract:

    Abstract This paper reports on a hybrid polymeric microfluidic device with optical detection for Droplet-based systems. The optical part of the device is integrated by a hybrid concept. The microfluidic structures were fabricated using CO 2 laser on poly methylmethacrylate (PMMA) substrate. The microfluidic network consists of two microchannels for forming Droplets of an aqueous liquid in an immiscible carrier liquid. The optical component consists of two optical fibers for guiding laser light from the source, through the detection point, to a photo diode. The formed Droplets pass the detection point and diffract the incoming laser light. The detected signal at the photo diode can be used for evaluating Droplet Size, Droplet shape, and Droplet formation frequency. The device can detect very high formation frequencies, which are not detectable using a conventional CCD camera/microscope setup.

  • optical detection for Droplet Size control in microfluidic Droplet based analysis systems
    International Conference on Solid-State Sensors Actuators and Microsystems, 2005
    Co-Authors: Namtrung Nguyen, Sumantri Lassemono, Franck Chollet
    Abstract:

    We report for the first time a hybrid polymeric microfluidic device with optical detection for microfluidic Droplet-based systems. The device consists of a fluidic part and an optical part. Microchannels were fabricated using CO/sub 2/ laser. The microfluidic part consists of two microchannels for forming Droplets of an aqueous liquid in an immiscible carrier liquid. The optical part consists of two optical fiber for light emission and light detection. MicroDroplets are formed, when the aqueous liquid is injected into the carrier flow. The formed bubbles pass the optical detection and diffract some of the incoming light. The detected signal from the other optical fiber can be evaluated for Droplet Size, Droplet shape, and Droplet formation frequency.

Butts, Thomas R - One of the best experts on this subject based on the ideXlab platform.

  • Spray Characterization and Herbicide Efficacy as Influenced by Pulse-width Modulation Sprayers
    DigitalCommons@University of Nebraska - Lincoln, 2018
    Co-Authors: Butts, Thomas R
    Abstract:

    Pesticide applications are a heavily scrutinized facet of today’s agricultural industry, and a concerted effort to optimize each application needs to be implemented. More precise and efficient pesticide applications are necessary to meet regulatory demands and increase economic efficiency through reduced pesticide inputs. Current pesticide application methods using precision technologies, including pulse-width modulation (PWM) sprayers, can assist with these goals. However, vast advancements in pesticide formulations, adjuvants, and nozzles, as well as the increasing popularity of PWM systems, have only increased the need for applied PWM and weed science research. Additionally, efforts have been placed on increasing spray Droplet Size to reduce particle drift, but this practice has led to reduced herbicide efficacy. Therefore, identifying an optimum herbicide Droplet Size which can reduce particle drift while simultaneously maintaining efficacy is a necessity. The objectives of this research were to: (1) identify the influence of application parameters on Droplet Size, Droplet exit velocity, nozzle tip pressure, and spray pattern uniformity from a PWM sprayer, (2) create best use PWM recommendations to optimize pesticide applications from these sprayers, (3) investigate the effect of spray Droplet Size and carrier volume on the efficacy of multiple herbicide solutions, (4) establish novel weed management recommendations based on an optimum Droplet Size, and (5) determine the plausibility of using PWM sprayers in site-specific weed management strategies. The results of this research have led to more precise PWM sprayer operation through clear and concise best use recommendations. The capability of PWM sprayers to make precise and uniform applications can assist with the reduction of spray particle drift and increase the overall application effectiveness. Additionally, site-specific weed management strategies were effectively established and optimum herbicide Droplet Sizes were estimated across a wide range of geographies and weed species. Although, convoluted interactions were identified between Droplet Size, carrier volume, and other application parameters in regards to their effect on herbicide efficacy. As a result of this research, applicators can more effectively utilize PWM sprayers, reduce herbicide inputs, mitigate spray particle drift, and reduce the selection pressure for the evolution of herbicide-resistant weeds

  • Spray Characterization and Herbicide Efficacy as Influenced by Pulse-Width Modulation Sprayers
    DigitalCommons@University of Nebraska - Lincoln, 2018
    Co-Authors: Butts, Thomas R
    Abstract:

    Pesticide applications are a heavily scrutinized facet of today’s agricultural industry, and a concerted effort to optimize each application needs to be implemented. More precise and efficient pesticide applications are necessary to meet regulatory demands and increase economic efficiency through reduced pesticide inputs. Current pesticide application methods using precision technologies, including pulse-width modulation (PWM) sprayers, can assist with these goals. However, vast advancements in pesticide formulations, adjuvants, and nozzles, as well as the increasing popularity of PWM systems, have only increased the need for applied PWM and weed science research. Additionally, efforts have been placed on increasing spray Droplet Size to reduce particle drift, but this practice has led to reduced herbicide efficacy. Therefore, identifying an optimum herbicide Droplet Size which can reduce particle drift while simultaneously maintaining efficacy is a necessity. The objectives of this research were to: (1) identify the influence of application parameters on Droplet Size, Droplet exit velocity, nozzle tip pressure, and spray pattern uniformity from a PWM sprayer, (2) create best use PWM recommendations to optimize pesticide applications from these sprayers, (3) investigate the effect of spray Droplet Size and carrier volume on the efficacy of multiple herbicide solutions, (4) establish novel weed management recommendations based on an optimum Droplet Size, and (5) determine the plausibility of using PWM sprayers in site-specific weed management strategies. The results of this research have led to more precise PWM sprayer operation through clear and concise best use recommendations. The capability of PWM sprayers to make precise and uniform applications can assist with the reduction of spray particle drift and increase the overall application effectiveness. Additionally, site-specific weed management strategies were effectively established and optimum herbicide Droplet Sizes were estimated across a wide range of geographies and weed species. Although, convoluted interactions were identified between Droplet Size, carrier volume, and other application parameters in regards to their effect on herbicide efficacy. As a result of this research, applicators can more effectively utilize PWM sprayers, reduce herbicide inputs, mitigate spray particle drift, and reduce the selection pressure for the evolution of herbicide-resistant weeds. Advisor: Greg R. Kruge